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Friction 2019, 7(1): 86-91 https://doi.org/10.1007/s40544-018-0210-1
Short Communication | Open Access | Issue | Published: 06 April 2018

The viscosity at the glass transition of a liquid lubricant

Show Author's Information Scott BAIR( )
Center for High-Pressure Rheology, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta GA 30332-0405, USA
Keywords:
elastohydrodynamic lubrication, glass transition, high pressure viscosity, EHL friction
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BAIR S. The viscosity at the glass transition of a liquid lubricant. Friction, 2019, 7(1): 86-91. https://doi.org/10.1007/s40544-018-0210-1
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Abstract Full text About this article

In the classical study of elastohydrodynamic lubrication (EHL) which does not employ real, measurable viscosity in analysis, the possibility of a glass transition has not been considered in many years. Indeed, the two rheological assumptions of classical EHL, the Newtonian inlet and the equivalence of a traction curve to a flow curve, would not have persisted so long had the pressure dependence of the viscosity been accurately stated. With the recent appearance of viscosity obtained from viscometers in EHL analysis, the possibility of a glass transition in the contact should be reexamined, especially for the fragile traction fluids. This article employs published data for a synthetic cycloaliphatic hydrocarbon to estimate the glass transition viscosity so that, when using real viscosities in EHL simulations, the state of the liquid may be assessed. Far into the glassy state the liquid should be treated as an elastic solid with a yield stress.


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About this article

The viscosity at the glass transition of a liquid lubricant

Show Author's information Scott BAIR( )
Center for High-Pressure Rheology, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta GA 30332-0405, USA

Abstract

In the classical study of elastohydrodynamic lubrication (EHL) which does not employ real, measurable viscosity in analysis, the possibility of a glass transition has not been considered in many years. Indeed, the two rheological assumptions of classical EHL, the Newtonian inlet and the equivalence of a traction curve to a flow curve, would not have persisted so long had the pressure dependence of the viscosity been accurately stated. With the recent appearance of viscosity obtained from viscometers in EHL analysis, the possibility of a glass transition in the contact should be reexamined, especially for the fragile traction fluids. This article employs published data for a synthetic cycloaliphatic hydrocarbon to estimate the glass transition viscosity so that, when using real viscosities in EHL simulations, the state of the liquid may be assessed. Far into the glassy state the liquid should be treated as an elastic solid with a yield stress.

Keywords: elastohydrodynamic lubrication, glass transition, high pressure viscosity, EHL friction

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Publication history

Received: 07 November 2017
Revised: 29 December 2017
Accepted: 29 January 2018
Published: 06 April 2018
Issue date: February 2019

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© The author(s) 2018

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This article is published with open access at Springerlink.com

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